Synthesis, Structures, and Properties of λ ⁵ -Phosphinine Functionalized with <i>p</i> -Benzoquinone

A 2,6-dicyano-λ⁵-phosphinine (DCNP) functionalized with <i>p</i>-benzoquinone (BQ) at the 4-position (<b>1</b>) has been successfully synthesized. X-ray structure analysis of <b>1</b> revealed that the DCNP and BQ moieties are significantly inclined to each other. Compound <b>1</b> exhibits ambipolar redox properties, being capable of forming both the radical cation and radical anion. Combined electrochemical and absorption/emission spectroscopic studies demonstrated that the nonemissive neutral species <b>1</b> and the emissive radical anion <b>1</b>^•- are reversibly interconvertible through electrochemical reduction and oxidation.